We track these items as they indicate the direction that we wll be paying for our raw materials in our precision machining shops, Steel, Aluminum, Brass and Stainless barstock. These items are critical to the manufacture of those materials.

When present in substantial amounts, Nickel provides a number of benefits to steel.

And its money too!

Nickel’s main contribution to steels is making them more forgiving of heat treatment variations. Think of it as the Heat Treater’s Friend.

Nickel lowers the critical temperatures, while widening the the temperature range for effective quenching and tempering. Nickel also retards the decomposiition of Austenite. Since nickel doesn’t form carbides, it doesn’t complicate the reheating for austenitizing process either.

Nickel contributes to an easier and more likely to be successful heat treatment.

Here are 5 Contributions Nickel makes to our alloy steel parts:

Improved toughness (especially at low temperatures!)

Simplified and more economical heat treatment (Money saved!)

Increased hardenability (depth of hardness achievable)

Less distortion during quenching (more good parts after Q&T!)

Improved corrosion resistance (See this link– 2.1 % of GDP lost to corrosion!)

In addition to its appearance in the credits for 43XX, 46XX, and 86XX alloy steel grades, Nickel is a major component of Stainless Steels, Invar, Monel, and Inconel.

Machinist hint: When you see Nickel as a major ingredient in steel, avoid tool dwell and light cuts. Nickel contributes to a material’s workhardening ability.

As machinists, we seldom encounter microalloy steels. but what do we need to know?

Microalloy steel is manufactured like any other, but the chemical ingredients added at the initial melt of the steel to make it a microalloy include elements like Vanadium, Columbium (sorry, Niobium for us IUPAC purists), Titanium, and higher amounts of Manganese and perhaps Molybdenum or Nickel.

Vanadium, Columbium Niobium, and Titanium are also grain refiners and aggressive Oxygen scavengers, so these steels tend to also have a very fine austenitic grain size.

In forgings, microalloy steels are able to develop higher mechanical properties (yield strengths greater than say 60,000 psi) and higher toughness as forged by just cooling in air or with a light mist water spray.

Normal alloy steels require a full austenitize, quench and temper heat treatment to develop properties greater than as rolled or cold worked.

Since microalloyed steels are able to get higher properties using forging process heat- rather than an additional heating quenching tempering cycle- they can be less expensive to process to get improved mechanical properties.

The developed microstructure ultimately makes the difference. The microstructure developed in the steel depends on the grade and type.

Tempered martensite for normal alloys.

Normal alloy steels require a transformation to martensite that is then tempered in order to achieve higher properties.

Bainite comparable hardness improved toughness.

Microalloy steel precipitates out various nitirides or carbides and may result in either a very fine ferrite- pearlite microstructure or may transform to bainite.

For machinists, if the steel is already at its hardest condition, the microalloyed microstructure of either ferrite pearlite or bainite is less abrasive than that of a fully quench and tempered alloy steel.

P.S. The non- martensitic structures also have higher toughness.

We don’t tend to machine prehardened steels in the precision machining industry, but if you ever are part of a team developing a process path for machining forgings, or finish cuts after induction hardening, these facts might be good to know.

Prices of raw materials used to make precision machined products are up substantially, ranging from 44% to 114% from March 2009- March 2010 for 6 of the 7 materials we track.

Low inventories, increasing demand, idled production facilities, are among the factors involved here in North America.

As are the historic iron ore agreement and continued high demand in China.

We think this trend will be around for a while...

Fuel price increases also impact freight, which is an important factor in our business.

We will not be shocked to see monies paid for steel in May to be $80 per ton higher than they were in April based on already announced price increases and the current price on #1 busheling which determines surcharges.

The weldability of steels is influenced primarily by the carbon content. At higher carbon levels, steels may need either pre- or post- weld heat treatment in order to prevent stress build up and weld cracking.

Generally speaking, if the Carbon Equivalent (CE) is 0.35 or below, no pre- or post- weld thermal treatment is needed. In our experience with maintenance welding, we have found that preheating was beneficial between 0.35 and 0.55 CE. Above 0.55 CE we usually both pre- and post- weld heated to relieve stress and prevent cracking.

So CE= .35 max.

However the other elements that are contained in the steel also have an effect on the steel’s “carbon equivalence.” These additional elements can really add up in scrap fed electric arc furnace steels that now predominate in our market.

This is the first formula I learned when I took over metallurgical support for maintenance ‘back in the day.’

In this formula you can see that 6 points of Manganese are approximately equal to one point of Carbon. 5 points of Chrome, Moly or Vanadium are roughly equal to a point of Carbon, while it takes about 15 points of Silicon, Nickel or Copper to get about the same effect as one point of Carbon.

The GE formula for Carbon Equivalency is CE= C+(Mn/6)+(Ni/20)+(Cr/10)+(Cu/40)+(Mo/50)+(Va/10). If this is less than .35 max, you should have no need to pre or post weld thermal treat in most cases.

As long as CE is no more than .35, you probably won’t need to preheat or post weld stress relieve your welded parts. above .35 CE, you may need either or both depending on section thickness and CE.

Welcome to our blog, Speaking of Precision. As Director of Technology and Industry Research for PMPA, I bring 38 years of hands-on experience in areas of manufacturing, quality and steelmaking. I help answer "HOW?","WITH WHAT?" and "REALLY?"